The present invention relates to a plasticized sulfur composition of improved thixotropy; in particular, a sulfur composition of increased viscosity prepared by including a C.sub.2 -C.sub.25 saturated, polyhydric alcohol in a plasticized sulfur mixture which is obtained by remelting a plasticized sulfur concentrate with added molten sulfur.
Plasticized sulfur mixtures are disclosed in various references. For example, J. I. Jin gives the following tabular comparison of plasticized sulfur compositions in his report given at the ACS Los Angeles meeting, Symposium on New Sulfur Chemistry, Apr. 19, 1974, page 235:
______________________________________ COMPARISON OF PLASTICIZED -SULFUR COMPOSITIONS (Refer- Plasticizer Melt Viscosity Regulator ence) ______________________________________ Mixture of dithiol Chlorinated Polyphenyls (2) and higher thiols Arylenepolysulfide (ZM-399)* and aliphatic poly- sulfide (LP-3)** None (3,6) ##STR1## Diphenyl dithiophosphate (4) and styrene Dithol Monomercaptan (5) ______________________________________ *Thiokol's styrene polysulfide **Thiokol's liquid polysulfide (2)Louthan, R.P., U.S. Pat. No. 3,434,852 (March 1969). (3)Barnes, M.D., U.S. Pat. No. 3,316,115 (April 1967). (4)Signouret, J.B., U.S. Pat. No. 3,560,451 (February 1971). (5)Kane, J.C., U.S. Pat. No. 3,447,941 (June 1969). (6)Dale, J.M., Report No. 1 (September 1961); Report No. 2 (April 1962); Report No.3 (June 1963), Project 10922, Southwest Research Institute.
Other reports of interest given at the above ACS Symposium on New Sulfur Chemistry include that by B. R. Currell et al, "Plasticization of Sulphur", which report was concerned with a study of the chemical interaction of additives (such as polymeric polysulfides, unsaturated hydrocarbons and phenolic derivatives) with sulfur and also measurement, using differential scanning calorimetry and electron microscopy, of the rate of crystallization of sulfur in the presence of these additives. Limonene, myrcene, dicyclopentadiene and cycloocta-1,3-diene were found particularly effective in retarding sulfur crystallization. Other reports at the ACS Symposium of interest include that by T. A. Sullivan et al, "The Use of Sulfur in Coatings and Structural Materials". The Sullivan et al report describes use of a sulfur formulation in construction of a cinder block building where the blocks were stacked dry and bonded together by spraying with the formulation.
U.S. Pat. No. 3,453,125 describes modifiers to reduce the viscosity of plasticized sulfur. According to the patent, the viscosity of plasticized sulfur compositions comprising elemental sulfur plasticized with an organic sulfur-plasticizing agent is reduced by the addition of a modifying amount of a persulfide of the formula EQU A--R--S.sub.x --R--A
wherein each R is a hydrocarbon radical having up to about 10 carbon atoms, at least one A is hydroxyl or carboxyl and x is an integer of from 2 to about 5.
According to U.S. Pat. No. 3,674,525, the viscosity of plasticized sulfur compositions comprising elemental sulfur plasticized with an organic sulfur-plasticizing agent is reduced by the addition of a modifying amount of an unsaturated acid or unsaturated acid anhydride to the plasticizing agent prior to its use for plasticizing sulfur.
U.S. Pat. No. 3,676,166 relates to viscosity control agents for thinning or reducing the high viscosity of molten plasticized sulfur wherein the control agent is selected from the group consisting of 1,2,4-trichlorobenzene; biphenyl; naphthalene; o-dichlorobenzene; p-dichlorobenzene; or xylene.
Other patents of interest include U.S. Pat. Nos. 3,371,072, 3,465,064, 3,560,451, 3,823,019, and 3,447,941. The last patent is concerned with sulfur road-marking compositions stable against degradation by heat and having a viscosity sufficiently low to permit application by spraying. The compositions comprise from about 40% to 96% elemental sulfur, from about 1% to about 20% of a sulfur-containing plasticizer, from about 0.05% to about 10% of a chain-terminating compound and from 0% to about 30% of a filler. The chain-terminating compound can be a monomercaptan, a monobasic acid monomercaptan, a polysulfide, or styrene. The monomercaptan is of the formula RSH, wherein R is selected from acyl and hydroxyalkyl of from 2 to 20 carbon atoms inclusive.